1. Field of the Invention
The present invention relates to a picking device for a fluid jet loom and, more particularly, to an automatic picking conditions regulating method and a device for carrying out the same for adjusting the weft yarn arrival crankshaft angle at the start and during the weaving operation of the loom.
2. Prior Art
It has been the conventional procedure of adjusting the weft yarn arrival crankshaft angle, when the weaving conditions are changed, to observe the traveling conditions of the weft yarn by means of a stroboscopic method or to measure the moment of arrival with a weft yarn arrival detector during the weaving operation, to display the measured results digitally, and to adjust the picking nozzle manually. Such a conventional procedure requires a long time and is unable to adjust the weft yarn arrival crankshaft angle properly and to adjust a plurality of looms in the same picking conditions. Accordingly, the looms are unable to operate at high efficiency and to weave high-quality woven fabrics.
Japanese Patent Laid-open Publication Nos. 56-96,938 and 56-107,046 (which respectively corresponds to U.S. Pat. Nos. 4,446,893 and 4,458,726) disclose inventions for adjusting the weft yarn arrival crankshaft angle to a target crankshaft angle by varying the picking fluid pressure or the rotating speed of the crankshaft. These inventions, however, are intended to adjust the weft yarn arrival crankshaft angle while the loom is operating. Accordingly, when the weaving conditions are changed, the picking conditions including the picking fluid pressure are set at the initial stage of the weaving operation on the basis of the previous experimental data or the result of measurement by the stroboscopic method.
According to the foregoing prior inventions, the weft yarn arrival crankshaft angle is adjusted through automatic control procedure after the loom has been started regardless of the value, provided that the controllable range is wide. However, when the control range is wide, the condition of control becomes transiently unstable during the process of control and, since the deviation of the crankshaft angle increases in the weaving operation after the adjustment of the crankshaft angle, the rapid and accurate regulation of the weft yarn arrival crankshaft angle within a target range is difficult.